Abstract
Y-12, 141 (0.1 ?? 0.3 mg/kg) given i.v. 1 min before the antigen challenge inhibited both the 48-hour passive cutaneous anaphylaxis (PCA) and active anaphylactic bronchoconstriction of rats mediated by IgE-like antibody. The anti-PCA activity of Y-12, 141 (0.3 mg/kg i.v.) given 1 min before the antigen challenge decreased significantly by predosing with Y-12, 141 (1 ?? 3 mg/kg i.v.) 60 min before the antigen challenge. The induction of tachyphylaxis in the PCA test appeared to depend on the doses and intervals between predosing and second dosing. The anti-PCA activity of disodium cromoglycate (DSCG) at a dose of 1 mg/kg i.v. decreased significantly by predosing with DSCG (10 mg/kg i.v.) 30 min before the antigen challenge. Cross -tachyphylaxis between Y-12, 141 and DSCG was observed in the PCA test. The tachyphylaxis to Y-12, 141 was more readily induced in the PCA than in the bronchoconstriction. The inhibitory activity of Y-12, 141 (0.3 mg/kg i.v.) given 1 min before the antigen challenge in the PCA and bronchoconstriction was not affected by predosing with Y-12, 141 (1 mg/kg p.o. or s.c.) for 7 days.
